Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
DHW Demand
DHW temperature control on MAX
Attach U-gauge to burner pressure test point
To set minimum burner pressure remove one lead from Modureg
To set maximum both leads on Modureg and DHW tap on full
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Can the burner pressure be adjusted to correct setting? Both must be set correctly (click link below for guidance).
To set up Burner Pressures on Gas Valve
11.8mbar MAX
2.5mbar MIN
Note:
When gauge is removed pressure test point should be tightened and checked for gas tightness.